1. Field
Example embodiments relate to a method of operating a memory device. Other example embodiments relate to a method of operating a phase-change memory device.
2. Description of the Related Art
There are several types of non-volatile memory devices including a flash memory, a ferroelectric RAM (FeRAM), a magnetic RAM (MRAM) and phase-change random access memories (PRAMs). A storage node of a PRAM is structurally different than other non-volatile memory devices.
A storage node of a PRAM includes a phase-change layer as a data storage layer. If a predetermined reset voltage is applied to the phase-change layer for a substantially short amount of time, a region of the phase-change layer changes to an amorphous region. If a predetermined set voltage is applied to the storage node for a substantially long amount of time, the amorphous region returns to a crystalline state.
Assuming that a first resistance pertains to the phase-change layer having an amorphous region and a second resistance pertains to the phase-change layer having no amorphous region, the first resistance is higher than the second resistance.
The PRAM is a memory device that writes and reads bit data using a phase-change layer having resistance characteristics that vary depending on the phase of the phase-change layer.
A conventional method of operating the PRAM may have a substantially slow operation speed because a set amount of time for the amorphous region to return to the crystalline state is relatively long.
In the conventional method of operating the PRAM, the characteristics of the phase-change layer may easily deteriorate by repeating the reset and set operations, shortening the durability (or endurance) of the PRAM.